MUSC study: Alzheimer’s disease linked to high-fat diets

Recent evidence suggests that metabolic disorders and many diseases frequently develop due to unhealthy lifestyles, such as poor diet and lack of physical activity.

Researchers Narayan R. Bhat, Ph.D., neurosciences professor at MUSC, and Lakshmi Thirumangalakudi, Ph.D., Department of Psychiatry, College of Physicians and Surgeons, Columbia University Medical Center and New York State Psychiatric Institute, have found evidence to suggest that what’s bad for the body is also bad for the mind. Their study was published this month in the Journal of Alzheimer's Disease.

“Alzheimer’s disease progressively robs its victims of their memory, mental faculties and independent living,” Bhat said. “Although specific genetic mutations have been identified that directly cause the disease, these cases are rare. Our study suggests potential common causes and co-morbidities of metabolic disorders and sporadic cases of Alzheimer’s disease and hence an opportunity to develop treatments targeted at improving insulin sensitivity for those more common cases of AD.”

Epidemiological and experimental studies point to a link between metabolic diseases and Alzheimer’s-like dementia via common vascular-associated risk factors. Although the underlying mechanisms are unclear and complex, certain common features are emerging including inflammation and insulin resistance, leading to changes in metabolic derangement in the brain similar to peripheral organs.

In fact, some researchers now describe Alzheimer’s as “type 3 diabetes” – a consequence of insulin deficiency and inaction (i.e., resistance). One of the consequences of altered insulin signaling and resistance in the brain is increased phosphorylation of tau, a brain protein that loses its normal function while becoming toxic in the Alzheimer’s disease brain.

In their study, Bhat and Thirumangalakudi describe brain changes that indicate altered insulin signaling and increased tau phosphorylation in normal mice fed a high-fat and high-cholesterol diet. The hypothesis for the link between vascular disorders and Alzheimer’s-like changes in the brain is that metabolic changes including peripheral inflammation and insulin resistance resulting from high fat intake cause dysfunction in the brain’s vascular system that in turn leads to cellular and metabolic changes in the brain similar to what occurs in an Alzheimer’s brain.